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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233// SPDX-License-Identifier: GPL-2.0-only/* * linux/drivers/char/ttyprintk.c * * Copyright (C) 2010 Samo Pogacnik */
/* * This pseudo device allows user to make printk messages. It is possible * to store "console" messages inline with kernel messages for better analyses * of the boot process, for example. */
#include <linux/console.h>#include <linux/device.h>#include <linux/serial.h>#include <linux/tty.h>#include <linux/module.h>#include <linux/spinlock.h>
struct ttyprintk_port { struct tty_port port; spinlock_t spinlock;};
static struct ttyprintk_port tpk_port;
/* * Our simple preformatting supports transparent output of (time-stamped) * printk messages (also suitable for logging service): * - any cr is replaced by nl * - adds a ttyprintk source tag in front of each line * - too long message is fragmented, with '\'nl between fragments * - TPK_STR_SIZE isn't really the write_room limiting factor, because * it is emptied on the fly during preformatting. */#define TPK_STR_SIZE 508 /* should be bigger then max expected line length */#define TPK_MAX_ROOM 4096 /* we could assume 4K for instance */#define TPK_PREFIX KERN_SOH __stringify(CONFIG_TTY_PRINTK_LEVEL)
static int tpk_curr;
static u8 tpk_buffer[TPK_STR_SIZE + 4];
static void tpk_flush(void){ if (tpk_curr > 0) { tpk_buffer[tpk_curr] = '\0'; printk(TPK_PREFIX "[U] %s\n", tpk_buffer); tpk_curr = 0; }}
static int tpk_printk(const u8 *buf, size_t count){ size_t i;
for (i = 0; i < count; i++) { if (tpk_curr >= TPK_STR_SIZE) { /* end of tmp buffer reached: cut the message in two */ tpk_buffer[tpk_curr++] = '\\'; tpk_flush(); }
switch (buf[i]) { case '\r': tpk_flush(); if ((i + 1) < count && buf[i + 1] == '\n') i++; break; case '\n': tpk_flush(); break; default: tpk_buffer[tpk_curr++] = buf[i]; break; } }
return count;}
/* * TTY operations open function. */static int tpk_open(struct tty_struct *tty, struct file *filp){ tty->driver_data = &tpk_port;
return tty_port_open(&tpk_port.port, tty, filp);}
/* * TTY operations close function. */static void tpk_close(struct tty_struct *tty, struct file *filp){ struct ttyprintk_port *tpkp = tty->driver_data;
tty_port_close(&tpkp->port, tty, filp);}
/* * TTY operations write function. */static ssize_t tpk_write(struct tty_struct *tty, const u8 *buf, size_t count){ struct ttyprintk_port *tpkp = tty->driver_data; unsigned long flags; int ret;
/* exclusive use of tpk_printk within this tty */ spin_lock_irqsave(&tpkp->spinlock, flags); ret = tpk_printk(buf, count); spin_unlock_irqrestore(&tpkp->spinlock, flags);
return ret;}
/* * TTY operations write_room function. */static unsigned int tpk_write_room(struct tty_struct *tty){ return TPK_MAX_ROOM;}
/* * TTY operations hangup function. */static void tpk_hangup(struct tty_struct *tty){ struct ttyprintk_port *tpkp = tty->driver_data;
tty_port_hangup(&tpkp->port);}
/* * TTY port operations shutdown function. */static void tpk_port_shutdown(struct tty_port *tport){ struct ttyprintk_port *tpkp = container_of(tport, struct ttyprintk_port, port); unsigned long flags;
spin_lock_irqsave(&tpkp->spinlock, flags); tpk_flush(); spin_unlock_irqrestore(&tpkp->spinlock, flags);}
static const struct tty_operations ttyprintk_ops = { .open = tpk_open, .close = tpk_close, .write = tpk_write, .write_room = tpk_write_room, .hangup = tpk_hangup,};
static const struct tty_port_operations tpk_port_ops = { .shutdown = tpk_port_shutdown,};
static struct tty_driver *ttyprintk_driver;
static struct tty_driver *ttyprintk_console_device(struct console *c, int *index){ *index = 0; return ttyprintk_driver;}
static struct console ttyprintk_console = { .name = "ttyprintk", .device = ttyprintk_console_device,};
static int __init ttyprintk_init(void){ int ret;
spin_lock_init(&tpk_port.spinlock);
ttyprintk_driver = tty_alloc_driver(1, TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_UNNUMBERED_NODE); if (IS_ERR(ttyprintk_driver)) return PTR_ERR(ttyprintk_driver);
tty_port_init(&tpk_port.port); tpk_port.port.ops = &tpk_port_ops;
ttyprintk_driver->driver_name = "ttyprintk"; ttyprintk_driver->name = "ttyprintk"; ttyprintk_driver->major = TTYAUX_MAJOR; ttyprintk_driver->minor_start = 3; ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE; ttyprintk_driver->init_termios = tty_std_termios; ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; tty_set_operations(ttyprintk_driver, &ttyprintk_ops); tty_port_link_device(&tpk_port.port, ttyprintk_driver, 0);
ret = tty_register_driver(ttyprintk_driver); if (ret < 0) { printk(KERN_ERR "Couldn't register ttyprintk driver\n"); goto error; }
register_console(&ttyprintk_console);
return 0;
error: tty_driver_kref_put(ttyprintk_driver); tty_port_destroy(&tpk_port.port); return ret;}
static void __exit ttyprintk_exit(void){ unregister_console(&ttyprintk_console); tty_unregister_driver(ttyprintk_driver); tty_driver_kref_put(ttyprintk_driver); tty_port_destroy(&tpk_port.port);}
device_initcall(ttyprintk_init);module_exit(ttyprintk_exit);
MODULE_DESCRIPTION("TTY driver to output user messages via printk");MODULE_LICENSE("GPL");